Local density of states around single vortices and vortex pairs: effect of boundaries and hybridization of vortex core states

TL;DR

This paper investigates how boundaries and vortex interactions influence the local density of states around vortices in mesoscopic superconductors, revealing complex interference effects that affect LDOS peak positions.

Contribution

It introduces a detailed analysis of quasiparticle interference effects on LDOS profiles near vortices, including boundary and vortex-vortex interactions, with potential experimental observability.

Findings

LDOS peak positions depend nontrivially on vortex separation and sample size

Interference effects cause LDOS peaks to shift away from vortex cores

Patterns are observable via scanning tunneling spectroscopy

Abstract

The profiles of local density of states (LDOS) around different vortex configurations in mesoscopic superconductors are studied taking account of the interference of quasiparticle waves experiencing Andreev reflection within the vortex cores and normal reflection at the boundaries or defects. For subgap energy levels these interference effects reveal themselves in a nontrivial dependence of the positions of the LDOS peaks on the intervortex distance and sample size: the peak positions generally do not coincide with the superconducting phase singularity points. The LDOS profiles are calculated for three generic examples: (i) vortex-vortex pair; (ii) vortex positioned near a flat boundary; (iii) vortex positioned in the center of a superconducting disk. The resulting evolution of the Andreev interference patterns could be observable by scanning tunneling spectroscopy techniques.